Sheetmetal forming method

ABSTRACT

A forming method for producing wall and ceiling cladding sheets from sheetmetal, wherein embossed patterns are pressed into a metal sheet so that they cover the entire surface area of the sheet substantially uniformly. In the method, the embossed pattern is formed from a number of flute portions oriented at an angle to each other and an intersection of these, the intersection and all the flute portions extending from it to a distance from the intersection being produced in a single embossing operation. In addition, the metal sheet is clamped from opposite sides in an area outside the embossed pattern and held in place so that the embossed pattern is mainly produced as a result of the sheet being stretched in the area of the embossed pattern, and the separately pressed embossed patterns are joined together in the areas of the flute portions.

The present invention relates to a sheetmetal forming method as definedin the preamble of claim 1.

Thin sheetmetal (e.g. sheet steel 0.5-1.5 mm and sheet aluminum 1-4 mm)is widely used as a cladding material in buildings, both on exteriorfaces and interior structures. A traditional practice is to use acassette structure in which metal sheets are cut and bent into the formof a cassette or box, and these are then screwed fast onto a studwork ofsteel or wood. The cassettes are mounted side by side and so that theypartly overlap at their edges to form a cladding as impervious aspossible, protecting the structures from rain and wind.

However, sheetmetal exterior claddings or cassettes used at present havesignificant drawbacks. To allow the cassette to be mounted in awatertight and neat-looking manner, the studwork structure supporting ithas to be precisely straight. Each cassette has to be fitted, positionedand screwed fast separately, so the mounting process is slow andlaborious.

At each corner point of the cassette, the cassette flanges mounted oneupon the other do not completely cover the entire area because they arefastened in a point-by-point manner, which is why there always remaincorner-point areas through which water may leak into the structure. Thisproblem can be reduced by setting separate seaming strips on the jointsas an extra operation.

The production costs of a cassette manufactured from sheetmetal arerelatively high because both cutting and bending operations are neededand additionally the percentage of wasted raw material is significantdue to the cutting. In the structure produced by cutting and bending,there always remain gaps at the corners, allowing water to leak into thestructure. Moreover, the sheet edges at the corner points remainuncoated and thus largely susceptible to corrosion. Besides, thecassettes have a relatively monotonous and simple appearance, andtherefore a wall surface made up of such cassettes is by no meanselegant in an architectural sense.

In addition, due to the cuts and corner structures, at least some of theedges of the cassette have to be made perpendicular to the cassettesurface, so adjacent cassettes will form slits of rectangularcross-section between them. Such slits are very unsatisfactory inlong-time use because they accumulate impurities, which start runningalong the cassette surfaces before long, thus producing traces that foulthe cassette wall structure and give it a disagreeable appearance.Therefore, traditional sheetmetal cassette wall structures would requirerelatively frequent washing to remain neat-looking, but as they aresusceptible to water leakages, they do not readily tolerate washing.Besides, cleaning during use is not general practice.

Another traditional procedure is to produce profiled metal sheets withrounded or angular flutes by pressing a sheetmetal web betweenappropriately shaped rotating rollers. In this way, long fluted sheetsare produced, and these are cut into desired lengths for use. This typeof profiled sheets are widely used as wall cladding material in variouswarehouse buildings in both rural and industrial areas, but they are notelegant enough to be commonly used as cladding material on the exteriorfaces of e.g. public buildings and institutions, where cassettestructures are generally used.

The object of the present invention is to overcome the drawbacks ofprior art. A specific object of the invention is to disclose a new typeof sheetmetal forming method that can be used to replace traditionalsheetmetal cassette structures with more variform and varying sheetmetalcladdings individually selected for and adapted to each application. Afurther object of the invention is to enable multidirectional andsimultaneous forming of metal sheets.

As for the features of the invention, reference is made to the claims.

In the sheetmetal forming method of the invention, to produce wall andceiling cladding sheets from sheetmetal, embossed patterns are pressedinto a metal sheet so that they cover the entire surface area of thesheet substantially uniformly. According to the invention, the embossedpattern is formed from a number of flute portions oriented at an angleto each other and an intersection of these, the intersection and all theflute portions extending from it to a distance from the intersectionbeing produced in a single embossing operation. In addition, the metalsheet is clamped from opposite sides outside the embossed pattern andmainly held in place so that the embossed pattern is mainly produced asa result of the sheet being stretched in the area of the embossedpattern. The embossed pattern to be formed may have a depth of the orderof up to 50 times the thickness of the blank.

Next, these embossed patterns arranged in a radial configuration andseparately pressed are joined together in the areas of the fluteportions, in other words, they are pressed into the metal sheet in suchmanner that the flute portions of adjacent embossed patterns overlapeach other to a sufficient degree so as to form continuous flutesbetween the intersections of adjacent embossed patterns. In this way,the embossed patterns consisting of the intersection and the fluteportions starting from it form in the metal sheet a network of flutes, acontinuous and repeated pattern consisting of flute intersections andflute portions connecting the intersections.

In an embodiment of the invention, the metal sheet is held clamped inthe area just immediately around the embossed pattern so that theembossed pattern is practically formed by only stretching the sheet inthe area of the embossed pattern. Another possibility, depending on theembossed pattern to be produced, is to hold the sheet clamped in an areainside the pattern as well.

In another embodiment of the invention, clamping is only applied to theedge areas of the metal sheet to be formed. Thus, the whole sheet can beclamped down at its edges, whereupon it is possible to form embossedpatterns in the sheet according to the invention so that an entire sheetpatterned in a desired manner is obtained.

Pressing the metal sheet and holding it in place preferably means thatthe pressing device has e.g. a lower tool and an upper tool which have ashape corresponding to the desired shapes of the metal sheet and betweenwhich the metal sheet is placed and stretched to form embossed patterns.At the same time, those portions or areas of the metal sheet that areclose to the embossed pattern or only the edge areas of the sheet areclamped between an upper and a lower part of a holding tool while theembossing process is going on, so that the metal sheet is practicallyonly stretched in the area of the embossed pattern and above all remainsstraight and uncreased during the forming.

The method of the invention uses a continuous, practically endless blanktaken from a coil or roll, and the blank is pressed and formed instages. Such a production process is very flexible and allows both smalland large series to be advantageously produced.

A sheet may preferably have two or more embossed patterns connected byflute portions to form a larger embossed pattern that comprises severalintersections and is produced by a single embossing operation, whichsignificantly accelerates the forming of the metal sheet. The embossedpattern produced by a single embossing operation may preferably have awidth covering the entire metal sheet, e.g. 1250 mm.

The lengths of the flute portions in the embossed patterns may vary orthey can preferably be variable in such manner that the distance betweenembossed patterns or their intersections can be adjusted as desirable indifferent applications. In this way, a checkered pattern of desired sizecan be formed in the metal sheet e.g. completely steplessly. Thus, in apreferred embodiment of the invention, the flute portions are at rightangles to each other and each embossed pattern has flute portionsextending in four directions from the intersection, so when thesepatterns are embossed and the flute portions of adjacent embossedpatterns merge, rectangular or maybe square fluting is formed in themetal sheet.

In a preferred embodiment of the invention, the intersection of theembossed pattern does not only consist of a junction between fluteportions; instead, an embossed area wider or larger than the flutes,e.g. a circular or square area is formed, the flute portions mergingwith the intersection at its edges. In this way, a more vivid and morevariform embossed pattern is produced.

Thus, an essential feature of the sheetmetal forming method of theinvention is that a given repeating embossed pattern is produced by astepwise embossing process, i.e. by forming one embossed pattern at atime, so that the embossed patterns in a completed sheet coversubstantially the entire sheet area either as a continuous network or asseparate and adjacent patterns. A further essential feature is thatsheet portions near the embossed pattern or at a distance from it areclamped and held in place during the embossing process so that theembossed patterns are mainly or substantially formed by stretching thesheet in the area of the embossed patterns only, thus allowing the sheetto remain straight and the patterns to be accurately aligned with eachother in spite of the stepwise nature of the embossing process.

As compared with prior art, the sheetmetal forming method of theinvention has significant advantages. By this method, it is possible toproduce large and continuous patterned sheetmetal surfaces, which meansthat the number of seams and joining areas is reduced and the sheets canbe mounted significantly faster and more easily. By using stamping,painting or another embossing technique, it is possible to give thecomplex of patterns thus formed a decorative appearance, e.g. imitatingdifferent facings, such as cleft-face stone or logos. Moreover, unlikeprior art solutions, the sheet can be mounted with either the reliefsurface or the recessed surface facing towards the observer.

In addition, the structure is very watertight because no cuts are neededand all edges of the sheets remain straight, with the result that noleakage points or exposed leakage points susceptible to corrosion areformed even at the corners of the joints. As compared with traditionalcassettes, the edges of different parts are tightened by virtue of theirshapes and the sheets being mounted with their edges partly overlappingeach other with a tight fit.

Significant advantages are achieved in respect of manufacturing costsbecause practically no cutting is needed but only stepwise pressing toshape and a ready-made sheet in desired size is obtained; the width isat most the width of the raw material web, and the length can be almostfreely defined.

The flutes used can be formed in suitable symmetric or unsymmetric,beveled or rounded shapes so that they will not gather impurities andfoul the whole structure as state-of-the-art cassettes do. Due to thelarge sheets and their rigid structure, the mountings are not requiredto be as accurately dimensioned as in prior art. Further, the panelsizes of the shapes, such as checkers, formed in the metal sheet can befreely chosen, which significantly facilitates the task of mounting thesheets as the sheets can be sized beforehand in accordance with thedimensions of the mount so that no cutting or severing is needed on theinstallation site.

In addition, besides straight surfaces, the invention also makes itpossible to create very tight, precise and accurately dimensionedcladding structures for curved surfaces e.g. in various containers, tanktowers and stairwells. Further, due to their possible large size andhigh rigidity, products manufactured by the method of the invention canalso be used as cladding e.g. on ceilings and noise barriers. Thanks tothe rigid structure, the cladding does not produce any clang or noise inwindy conditions as traditional cassette structures do.

In the following, the invention will be described in detail withreference to the attached drawings, wherein

FIG. 1 presents a prior-art cassette structure, and

FIG. 2 presents a metal sheet produced by the method of the invention.

FIG. 1 presents a prior-art standard cassette type widely used atpresent. The cassette is made by cutting and bending a metal sheet. Inaddition to being slow and laborious to produce, the cassette hascorrosion-prone cut corners 1 and holes 3. In addition, the open cornersland exposed corner areas 4 constitute bad leakage points in thestructure. Cassette sizes generally vary between 300×400 and 1000×2000mm, so when small cassettes are used, the cost of installation work is asignificant proportion of total costs.

FIG. 2 presents a metal sheet produced by the method of the invention.The raw material used is e.g. a sheetmetal band which may have a widthof 200 . . . 1500 mm in the widthways direction of the figure and analmost endless length in the vertical direction of the figure. Accordingto the invention, each embossed pattern 5 consists of an intersection 6and four flute portions 7 starting from it at an angle of 90° to eachother.

The size of the embossed pattern 5 is such that two adjacent embossedpatterns pressed at separate times clearly overlap each other. Thisensures that the flute portions of two adjacent embossed patterns willprecisely merge into a single continuous flute portion connecting twointersections. In this embodiment, the flute portions have the form ofan equilateral trapezoid, but they may have varying forms, being almostrectangular, round, round-cornered or suitable combinations of these.

In the lower part of FIG. 2 is depicted an individual rectangularembossed pattern 5, in which the slashed areas 8 represent the areaswhere the metal sheet is held fast and clamped by means of a suitableholding tool while the flute portions and the intersection are beingpressed and formed between these areas 8. Another possibility is toclamp the sheet and hold it in place by applying a clamping force to itsedge areas 9 only.

The result obtained in this embodiment is a single and continuous formedsheetmetal product of desired length that corresponds to a plurality oftraditional separate cassettes. It can be fastened using only a fewscrews. It has no corrosion-prone cuts except for the outer edges. Itcomprises very few seams, thus minimizing potential leakage points.

In the foregoing, the invention has been described by way of examplewith reference to the attached drawings while different embodiments ofthe invention are possible in the scope defined in the claims.

1. Forming method for producing wall and ceiling cladding sheets fromsheetmetal, wherein embossed patterns are pressed into a metal sheet sothat they cover the entire surface area of the sheet substantiallyuniformly, wherein the embossed pattern is formed from a number of fluteportions oriented at an angle to each other and an intersection ofthese, the intersection and all the flute portions extending from it toa distance from the intersection being produced in a single embossingoperation, the metal sheet is clamped from opposite sides in an areaoutside the embossed pattern and mainly held in place so that theembossed pattern is mainly produced as a result of the sheet beingstretched in the area of the embossed pattern, and the separatelypressed embossed patterns are joined together in the areas of the fluteportions.
 2. Forming method according to claim 1, wherein a flutenetwork consisting of flute intersections and flute portions connectingthe intersections is formed in the metal sheet from the embossedpatterns consisting of an intersection and flute portions starting fromit.
 3. Forming method according to claim 1, wherein two embossedpatterns connected by a common flute portion are pressed simultaneously.4. Forming method according to claim 1, wherein a number of embossedpatterns connected by flute portions are pressed simultaneously. 5.Forming method according to claim 1, wherein the length of the fluteportion in the embossed pattern is adjusted to adjust the distancebetween the embossed patterns, i.e. the distance between theintersections in the formed metal sheet.
 6. Forming method according toclaim 1, wherein the flute portions are at right angles to each other inthe embossed pattern so that a rectangular, preferably square fluting ispressed into the metal sheet.
 7. Forming method according to claim 1,wherein only straight flute portions are used.
 8. Forming methodaccording to claim 1, wherein an area wider than the flutes, such as acircular or rectangular area is formed at the intersection.
 9. Formingmethod according to claim 1, wherein the metal sheet is held clamped inthe areas immediately around the embossed pattern so that the embossedpattern is practically formed by the sheet being stretched in the areaof the embossed pattern only.
 10. Forming method according to claim 1,wherein the metal sheet is held clamped in the edge areas of the entiremetal sheet to be formed.